Cucumber Hybrid Enki

ABSTRACT

A hybrid cucumber designated Enki is disclosed having resistance to powdery mildew ( Sphaerotheca fuliginea ), cucumber mosaic virus, and cucumber vein yellowing virus. The invention relates to the seeds of hybrid cucumber Enki, to the plants of hybrid cucumber Enki, and to methods for producing a cucumber plant, either inbred or hybrid, by crossing the hybrid Enki with itself or another cucumber plant. The invention further relates to methods for producing a cucumber plant containing in its genetic material one or more transgenes and to the transgenic plants produced by that method and to methods for producing other cucumber lines, cultivars, or hybrids derived from the hybrid cucumber Enki.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinctive cucumber hybrid designated Enki which is a parthenocarpic slicing cucumber that also has intermediate resistance to powdery mildew, cucumber mosaic virus, and cucumber vein yellowing virus. All publications cited in this application are herein incorporated by reference.

There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The selected germplasm is crossed in order to recombine the desired traits and through selection varieties or parent lines are developed. The goal is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm. These important traits may include higher yield, field performance, fruit and agronomic quality, such as fruit shape and length, resistance to diseases and insects, and tolerance to drought and heat.

Practically speaking, all cultivated forms of cucumber belong to the highly polymorphic species Cucumis sativus L. that is grown for its edible fruit. As a crop, cucumbers are grown commercially wherever environmental conditions permit the production of an economically viable yield. They can be hand or mechanically harvested. Cucumbers that are grown for fresh market, also called slicers, are generally hand harvested. Those that are to be processed are called “picklers” and may be hand or mechanically harvested. They are produced on trailing or climbing vines. On healthy plants there is a canopy of large, regular, three-lobed leaves in an alternate arrangement. Pickling cucumbers grown in the United States have usually blunt and angular fruits. They are white-spined and most possess dark green or medium dark green exterior color. Most slicers have slightly rounded ends and taper slightly from the stem to blossom end. However, cylindrical-shaped fruits with blocky or even rounded ends are also available.

Many changes that occurred with the domestication of the cucumber relate to fruit morphology, with a specialization in fruit shape and size. Slicing cucumbers are frequently sold in lengths from 15 cm to 25 cm and diameter varies from 2.5 cm to nearly 7 cm. In the United States, the principal slicer cucumber growing regions are Georgia, Florida, Michigan, California, and North Carolina, with nearly 42,000 acres out of a U.S. total acreage of 57,500 acres. The main states that produce processing cucumbers are Michigan, North Carolina, and Texas. Fresh cucumbers are available in the United States mainly from spring to fall. Cucumbers are consumed in many forms; generally processed for pickling types and as fresh market product for slicers. Although slicing cultivars may be processed, they generally are not acceptable substitutes for the pickling cucumbers.

Cucumis sativus is a member of the family Cucurbitaceae. The Cucurbitaceae is a family of about 90 genera and 700 to 760 species, mostly of the tropics. The family includes melons, pumpkins, squashes, gourds, watermelon, loofah, and many weeds. The genus Cucumis, to which the cucumber and several melons belong, includes about 70 species. The cucumber is believed to be native to India or Southern Asia and has been cultivated there for about 3000 years.

Cucumber is distinct from other Cucumis species in that it has seven pairs of chromosomes (2n=2x=14) whereas most others have twelve pairs or multiples of twelve. Pollination techniques for controlled crosses in cucumbers are easy to conduct. If bees and natural pollen vectors can be excluded, the breeder need not be concerned about preventing selfing or other pollen contamination because of the diclinous nature of cucumbers and the stickiness or adherence of pollen to its source flower. There is no wind dissemination of pollen. Pistillate flowers are receptive in the morning or up to midday on the day they open. Cucumbers have a broad range of floral morphologies, from staminate, pistillate to hermaphrodite flowers, yielding several types of sex expression.

Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F₁ hybrid cultivar, pureline cultivar, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, and recurrent selection.

The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination, and the number of hybrid offspring from each successful cross.

Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).

Promising advanced breeding lines are thoroughly tested and compared to appropriate standards in environments representative of the commercial target area(s) for at least three years. The best lines are candidates for new commercial cultivars. Those lines still deficient in a few traits are used as parents to produce new populations for further selection.

These processes, which lead to the final step of marketing and distribution, usually take from ten to twenty years from the time the first cross or selection is made. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.

A most difficult task is the identification of individuals that are genetically superior because, for most traits, the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a single observation is inconclusive, replicated observations provide a better estimate of its genetic worth.

The goal of cucumber plant breeding is to develop new, unique, and superior cucumber cultivars and hybrids. The breeder initially selects and crosses two or more parental lines, followed by repeated selfing and selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing, and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop the same line, or even very similar lines, having the same cucumber traits.

Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic, and soil conditions, and further selections are then made during and at the end of the growing season. The cultivars or hybrids that are developed are unpredictable because the breeder's selection occurs in unique environments with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. The same breeder cannot produce the same cultivar twice by using the same original parents and the same selection techniques. This unpredictability results in the expenditure of large amounts of research monies to develop superior new cucumber cultivars and hybrids.

The development of commercial cucumber cultivars requires the development of cucumber parental lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop cultivars from breeding populations. Breeding programs combine desirable traits from two or more varieties or various broad-based sources into breeding pools from which lines are developed by selfing and selection of desired phenotypes. The new lines are crossed with other lines and the hybrids from these crosses are evaluated to determine which have commercial potential.

Pedigree breeding is used commonly for the improvement of self-pollinating crops or inbred lines of cross-pollinating crops. Two parents which possess favorable, complementary traits are crossed to produce an F₁. An F₂ population is produced by selfing one or several F₁s or by intercrossing two F₁s (sib mating). Selection of the best individuals is usually begun in the F₂ population. Then, beginning in the F₃, the best individuals in the best families are selected. Replicated testing of families, or hybrid combinations involving individuals of these families, often follows in the F₄ generation to improve the effectiveness of selection for traits with low heritability. At an advanced stage of inbreeding (i.e., F₆ and F₇), the best lines or mixtures of phenotypically similar lines are tested for potential release as new cultivars.

Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.

Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or line that is the recurrent parent. The source of the trait to be transferred is called the donor parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.

The single-seed descent procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one-seed sample to plant the next generation. When the population has been advanced from the F₂ to the desired level of inbreeding, the plants from which lines are derived will each trace to different F₂ individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F₂ plants originally sampled in the population will be represented by a progeny when generation advance is completed.

In addition to phenotypic observations, the genotype of a plant can also be examined. There are many laboratory-based techniques available for the analysis, comparison, and characterization of plant genotype. Among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length polymorphisms (AFLPs), Simple Sequence Repeats (SSRs—which are also referred to as Microsatellites), and Single Nucleotide Polymorphisms (SNPs).

Isozyme Electrophoresis and RFLPs have been widely used to determine genetic composition. Shoemaker and Olsen (Molecular Linkage Map of Soybean (Glycine max), pp. 6.131-6.138 in S. J. O'Brien (Ed.) Genetic Maps: Locus Maps of Complex Genomes, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1993)), developed a molecular genetic linkage map that consisted of 25 linkage groups with about 365 RFLP, 11 RAPD, three classical markers, and four isozyme loci. See also, Shoemaker, R. C., RFLP Map of Soybean, pp. 299-309, in Phillips, R. L. and Vasil, I.K. (Eds.), DNA-Based Markers in Plants, Kluwer Academic Press, Dordrecht, the Netherlands (1994).

SSR technology is currently the most efficient and practical marker technology; more marker loci can be routinely used and more alleles per marker locus can be found using SSRs in comparison to RFLPs. For example, Diwan and Cregan described a highly polymorphic microsatellite locus in soybean with as many as 26 alleles. Diwan, N. and Cregan, P. B., Theor. Appl. Genet., 95:22-225 (1997). SNPs may also be used to identify the unique genetic composition of the invention and progeny varieties retaining that unique genetic composition. Various molecular marker techniques may be used in combination to enhance overall resolution.

Molecular markers, which include markers identified through the use of techniques such as Isozyme Electrophoresis, RFLPs, RAPDs, AP-PCR, DAF, SCARs, AFLPs, SSRs, and SNPs, may be used in plant breeding. One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome.

Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select toward the genome of the recurrent parent and against the markers of the donor parent. This procedure attempts to minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program. The use of molecular markers in the selection process is often called genetic marker enhanced selection or marker-assisted selection. Molecular markers may also be used to identify and exclude certain sources of germplasm as parental varieties or ancestors of a plant by providing a means of tracking genetic profiles through crosses.

Mutation breeding is another method of introducing new traits into cucumber varieties. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation (such as X-rays, Gamma rays, neutrons, Beta radiation, or ultraviolet radiation), chemical mutagens (such as base analogs like 5-bromo-uracil), antibiotics, alkylating agents (such as sulfur mustards, nitrogen mustards, epoxides, ethyleneamines, sulfates, sulfonates, sulfones, or lactones), azide, hydroxylamine, nitrous acid, or acridines. Once a desired trait is observed through mutagenesis, the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in Principles of Cultivar Development by Fehr, Macmillan Publishing Company (1993).

The production of double haploids can also be used for the development of homozygous varieties in a breeding program. Double haploids are produced by the doubling of a set of chromosomes from a heterozygous plant to produce a completely homozygous individual. For example, see Wan, et al., Theor. Appl. Genet., 77:889-892 (1989).

Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Principles of Plant Breeding, John Wiley and Son, pp. 115-161 (1960); Allard (1960); Simmonds (1979); Sneep, et al. (1979); Fehr (1987); “Carrots and Related Vegetable Umbelliferae,” Rubatzky, V. E., et al. (1999)).

Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor, and consumer for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.

Cucumber is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop stable, high yielding cucumber hybrids that are agronomically sound. To accomplish this goal, the cucumber breeder must select and develop cucumber plants that have the traits that result in superior parental lines for producing hybrids.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.

SUMMARY OF THE INVENTION

The following embodiments and aspects thereof are described in conjunction with systems, tools, and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

According to the invention, there is provided a hybrid cucumber plant designated Enki. This invention thus relates to the seeds of hybrid cucumber Enki, to the plants of cucumber Enki, to methods for producing a cucumber plant produced by crossing hybrid cucumber Enki with itself or another cucumber plant, and to methods for producing a cucumber plant containing in its genetic material one or more transgenes and to the transgenic cucumber plants produced by that method. This invention also relates to methods for producing other cucumber cultivars or hybrids derived from hybrid cucumber Enki and to the cucumber cultivars and hybrids derived by the use of those methods. This invention further relates to cucumber seeds and plants produced by crossing hybrid cucumber Enki with another cucumber cultivar.

Parts of the cucumber plant of the present invention are also provided, for example, but not limited to, pollen, ovule, fruit, cells, embryos, meristems, cotyledons, leaves, anthers, roots, root tips, pistil, flower, seed, and stalks.

In another aspect, the present invention provides regenerable cells for use in tissue culture of hybrid cucumber plant Enki. The tissue culture will preferably be capable of regenerating plants having the physiological and morphological characteristics of the foregoing cucumber plant, and of regenerating plants having substantially the same genotype as the foregoing inbred cucumber plant. Preferably, the regenerable cells in such tissue cultures will be produced from embryo, protoplast, meristematic cell, callus, pollen, leaf, stem, petiole, root, root tip, fruit, seed, flower, anther, pistil, or the like. Still further, the present invention provides cucumber plants regenerated from tissue cultures of the invention.

Another objective of the invention is to provide methods for producing other cucumber plants derived from hybrid cucumber Enki. Cucumber cultivars and hybrids derived by the use of those methods are also part of the invention.

The invention also relates to methods for producing a cucumber plant containing in its genetic material one or more transgenes and to the transgenic cucumber plant produced by that method.

In another aspect, the present invention provides for single gene converted plants of hybrid cucumber Enki. The single transferred gene may preferably be a dominant or recessive allele. Preferably, the single transferred gene will confer such trait as sex determination, herbicide resistance, insect resistance, resistance for bacterial, fungal, or viral disease, improved harvest characteristics, enhanced nutritional quality, or improved agronomic quality. The single gene may be a naturally occurring cucumber gene or a transgene introduced through genetic engineering techniques.

The invention further provides methods for developing cucumber plants in a cucumber plant breeding program using plant breeding techniques including recurrent selection, backcrossing, pedigree breeding, restriction fragment length polymorphism enhanced selection, genetic marker enhanced selection, and transformation. Marker loci, such as restriction fragment polymorphisms or random amplified DNA, have been published for many years and may be used for selection. See, Pierce, et al., HortScience, 25:605-615 (1990); Wehner, T., Cucurbit Genetics Cooperative Report, 20: 66-88 (1997); and Kennard, et al., Theorical Applied Genetics, 89:217-224 (1994). Seeds, cucumber plants, and parts thereof produced by such breeding methods are also part of the invention.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference by study of the following descriptions.

Definitions

In the description and tables that follow, a number of terms are used. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:

Allele. The allele is any of one or more alternative forms of a gene, all of which relate to one trait or characteristic. In a diploid cell or organism, the two alleles of a given gene occupy corresponding loci on a pair of homologous chromosomes.

Androecious plant. A plant having staminate flowers only.

Backcrossing. Backcrossing is a process in which a breeder repeatedly crosses hybrid progeny back to one of the parents, for example, a first generation hybrid F₁ with one of the parental genotype of the F₁ hybrid.

Blossom end. The blossom end is the distal end of the fruit where the flower blossom is located (i.e., the “far” end as measured from the base of the plant). The other end of a fruit is the stem end.

Blossom scar. The blossom scar is the small mark left on the distal end of the fruit after the flower falls off.

Blunt ends. Blunt ends are ends of the cucumber fruits that are not tapered or rounded.

Covered cultivation. Any type of cultivation where the plants are not exposed to direct sunlight. The covering includes, but is not limited to, greenhouses, glasshouses, nethouses, plastic houses, and tunnels.

Essentially all the physiological and morphological characteristics. A plant having essentially all the physiological and morphological characteristics means a plant having the physiological and morphological characteristics of the recurrent parent, except for the characteristics derived from the converted gene.

Gene. As used herein, “gene” refers to a segment of nucleic acid. A gene can be introduced into a genome of a species, whether from a different species or from the same species, using transformation or various breeding methods.

Gynoecious plant. A plant having pistillate flowers only.

Indeterminate vine or indeterminate growth. Refers to apical meristem producing an unrestricted number of lateral organs; characteristic of vegetative apical meristems. (Anatomy of Seed Plants, 2nd Edition, John Wiley and Sons, p. 513 (1977). The main stem of the plant continues to grow as long as the plant stays healthy, as opposed to a determinate plant, which at some point in its life cycle will stop growing longer.

Monoecious plant. A plant having separate staminate and pistillate flowers on the same plant.

Parthenocarpic. “Parthenocarpic” refers to the ability of fruit to develop without pollination or fertilization. The fruit are therefore seedless.

Percent identity. Percent identity as used herein refers to the comparison of the homozygous alleles of two cucumber lines, hybrids, or varieties. Percent identity is determined by comparing a statistically significant number of the homozygous alleles of two developed varieties, lines, or hybrids. For example, a percent identity of 90% between cucumber plant 1 and cucumber plant 2 means that the two plants have the same allele at 90% of their loci.

Percent similarity. Percent similarity as used herein refers to the comparison of the homozygous alleles of a cucumber plant such as hybrid cucumber Enki with another plant, and if the homozygous allele of hybrid cucumber Enki matches at least one of the alleles from the other plant then they are scored as similar. Percent similarity is determined by comparing a statistically significant number of loci and recording the number of loci with similar alleles as a percentage. A percent similarity of 90% between hybrid cucumber Enki and another plant means that hybrid cucumber Enki matches at least one of the alleles of the other plant at 90% of the loci.

Propagate. To “propagate” a plant means to reproduce the plant by means including, but not limited to, seeds, cuttings, divisions, tissue culture, embryo culture, or other in vitro method.

Quantitative trait loci (QTL). Quantitative trait loci refer to genetic loci that control to some degree numerically representable traits that are usually continuously distributed.

Regeneration. Regeneration refers to the development of a plant from tissue culture.

Single gene converted. Single gene converted or conversion plant refers to plants which are developed by a plant breeding technique called backcrossing wherein essentially all of the desired morphological and physiological characteristics of an inbred are recovered in addition to the single gene transferred into the inbred via the backcrossing technique, genetic engineering, or mutation.

Transgene. A “transgene” is a gene taken or copied from one organism and inserted into another organism. A transgene may be a gene that is foreign to the receiving organism or it may be a modified version of a native, or endogenous, gene.

Vertical growing system. A “vertical growing system” means a plant growing technique in which plants are grown vertical to the ground with the use of supporting material. The supporting material includes, but is not limited to, wires or nets.

DETAILED DESCRIPTION OF THE INVENTION

Hybrid cucumber Enki is a slicer cucumber with superior characteristics. Hybrid cucumber Enki is intended for covered cultivation during the spring. Hybrid cucumber Enki is moderately resistant to powdery mildew (Podosphaera xanthii) and cucumber mosaic virus (CMV), and is resistant to cucumber vein yellowing virus (CVYV).

Enki is a cucumber hybrid with high yield potential and medium fruit with dark-green skin. The hybrid has shown uniformity and stability for the traits, within the limits of environmental influence for the traits. Hybrid cucumber Enki has been increased with continued observation for uniformity. No variant traits have been observed or are expected in Enki.

Hybrid cucumber Enki has the following morphologic and other characteristics.

TABLE 1 VARIETY DESCRIPTION INFORMATION Type: Predominant usage: Fresh market Predominant culture: Greenhouse Fruit type: American slicer Plant: Growing season: Spring Sex expression: Gynoecious Parthenocarpy: Present Time of development of female flowers (80% of plants with at least one female flower): Early Ovary, color of vestiture: White Fruit (young): Type of vestiture: Prickles only Fruit (at market maturity): Length: Medium Predominant shape of stem end: Acute Length of neck: Very short Ground color of skin: Green Intensity of ground color of skin: Dark Ribs: Absent or weak Cotyledon bitterness: Absent Disease Resistance: Cucumber scab (Cladosporium cucumerinum): Susceptible Powdery mildew (Podosphaera xanthii): Moderately resistant Downy Mildew (Pseudoperonospora cubensis): Susceptible Corynespora blight and target spot (Corynespora cassiicola): Susceptible Cucumber mosaic virus (CMV): Moderately resistant Cucumber vein yellowing virus (CVYV): Resistant Zucchini yellows mosaic virus (ZYMV): Susceptible

Furhter Embodiments of the Invention

This invention also is directed to methods for producing a cucumber plant by crossing a first parent cucumber plant with a second parent cucumber plant wherein either the first or second parent cucumber plant is a hybrid cucumber plant of Enki. Further, both first and second parent cucumber plants can come from the hybrid cucumber Enki. All plants produced using hybrid cucumber Enki as a parent are within the scope of this invention, including plants derived from hybrid cucumber Enki.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which cucumber plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, ovules, flowers, leaves, stems, and the like.

With the advent of molecular biological techniques that have allowed the isolation and characterization of genes that encode specific protein products, scientists in the field of plant biology developed a strong interest in engineering the genome of plants to contain and express foreign genes, or additional, or modified versions of native, or endogenous, genes (perhaps driven by different promoters) in order to alter the traits of a plant in a specific manner. Such foreign additional and/or modified genes are referred to herein collectively as “transgenes.” Over the last fifteen to twenty years several methods for producing transgenic plants have been developed, and the present invention, in particular embodiments, also relates to transformed versions of the claimed cultivar.

Plant transformation involves the construction of an expression vector that will function in plant cells. Such a vector includes DNA comprising a gene under control of, or operatively linked to, a regulatory element (for example, a promoter). The expression vector may contain one or more such operably linked gene/regulatory element combinations. The vector(s) may be in the form of a plasmid, and can be used alone or in combination with other plasmids, to provide transformed cucumber plants, using transformation methods as described below to incorporate transgenes into the genetic material of the cucumber plant(s).

Expression Vectors for Cucumber Transformation: Marker Genes

Expression vectors include at least one genetic marker, operably linked to a regulatory element (for example, a promoter) that allows transformed cells containing the marker to be either recovered by negative selection (i.e., inhibiting growth of cells that do not contain the selectable marker gene), or by positive selection (i.e., screening for the product encoded by the genetic marker). Many commonly used selectable marker genes for plant transformation are well known in the transformation arts, and include, for example, genes that code for enzymes that metabolically detoxify a selective chemical agent which may be an antibiotic or a herbicide, or genes that encode an altered target which is insensitive to the inhibitor. A few positive selection methods are also known in the art.

One commonly used selectable marker gene for plant transformation is the neomycin phosphotransferase II (nptll) gene, isolated from transposon Tn5, which when placed under the control of plant regulatory signals, confers resistance to kanamycin (Fraley, et al., PNAS, 80:4803 (1983)). Another commonly used selectable marker gene is the hygromycin phosphotransferase gene which confers resistance to the antibiotic hygromycin (Vanden Elzen, et al., Plant Mol. Biol., 5:299 (1985)).

Additional selectable marker genes of bacterial origin that confer resistance to antibiotics include gentamycin acetyl transferase, streptomycin phosphotransferase, aminoglycoside-3′-adenyl transferase, the bleomycin resistance determinant (Hayford, et al., Plant Physiol., 86:1216 (1988); Jones, et al., Mol. Gen. Genet., 210:86 (1987); Svab, et al., Plant Mol. Biol., 14:197 (1990); Hille, et al., Plant Mol. Biol.; 7:171 (1986)). Other selectable marker genes confer resistance to herbicides such as glyphosate, glufosinate, or bromoxynil (Comai, et al., Nature, 317:741-744 (1985); Gordon-Kamm, et al., Plant Cell, 2:603-618 (1990); Stalker, et al., Science, 242:419-423 (1988)).

Selectable marker genes for plant transformation that are not of bacterial origin include, for example, mouse dihydrofolate reductase, plant 5-enolpyruvylshikimate-3-phosphate synthase and plant acetolactate synthase (Eichholtz, et al., Somatic Cell Mol. Genet., 13:67 (1987); Shah, et al., Science, 233:478 (1986); Charest, et al., Plant Cell Rep., 8:643 (1990)).

Another class of marker genes for plant transformation requires screening of presumptively transformed plant cells rather than direct genetic selection of transformed cells for resistance to a toxic substance such as an antibiotic. These genes are particularly useful to quantify or visualize the spatial pattern of expression of a gene in specific tissues and are frequently referred to as reporter genes because they can be fused to a gene or gene regulatory sequence for the investigation of gene expression. Commonly used genes for screening presumptively transformed cells include α-glucuronidase (GUS), α-galactosidase, luciferase and chloramphenicol, acetyltransferase (Jefferson, R. A., Plant Mol. Biol. Rep., 5:387 (1987); Teeri, et al., EMBO J., 8:343 (1989); Koncz, et al., PNAS, 84:131 (1987); DeBlock, et al., EMBO J., 3:1681 (1984)).

In vivo methods for visualizing GUS activity that do not require destruction of plant tissues are available (Molecular Probes, Publication 2908, IMAGENE GREEN, pp. 1-4 (1993) and Naleway, et al., J. Cell Biol., 115:151a (1991)). However, these in vivo methods for visualizing GUS activity have not proven useful for recovery of transformed cells because of low sensitivity, high fluorescent backgrounds, and limitations associated with the use of luciferase genes as selectable markers.

More recently, a gene encoding Green Fluorescent Protein (GFP) has been utilized as a marker for gene expression in prokaryotic and eukaryotic cells (Chalfie, et al., Science, 263:802 (1994)). GFP and mutants of GFP may be used as screenable markers.

Expression Vectors for Cucumber Transformation: Promoters

Genes included in expression vectors must be driven by a nucleotide sequence comprising a regulatory element (for example, a promoter). Several types of promoters are now well known in the transformation arts, as are other regulatory elements that can be used alone or in combination with promoters.

As used herein, “promoter” includes reference to a region of DNA upstream from the start of transcription and involved in recognition and binding of RNA polymerase and other proteins to initiate transcription. A “plant promoter” is a promoter capable of initiating transcription in plant cells. Examples of promoters under developmental control include promoters that preferentially initiate transcription in certain tissues, such as leaves, roots, seeds, fibers, xylem vessels, tracheids, or sclerenchyma. Such promoters are referred to as “tissue-preferred.” Promoters which initiate transcription only in certain tissue are referred to as “tissue-specific.” A “cell type” specific promoter primarily drives expression in certain cell types in one or more organs, for example, vascular cells in roots or leaves. An “inducible” promoter is a promoter which is under environmental control. Examples of environmental conditions that may effect transcription by inducible promoters include anaerobic conditions or the presence of light. Tissue-specific, tissue-preferred, cell type specific, and inducible promoters constitute the class of “non-constitutive” promoters. A “constitutive” promoter is a promoter which is active under most environmental conditions.

A. Inducible Promoters:

An inducible promoter is operably linked to a gene for expression in cucumber. Optionally, the inducible promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in cucumber. With an inducible promoter the rate of transcription increases in response to an inducing agent.

Any inducible promoter can be used in the instant invention. See, Ward, et al., Plant Mol. Biol., 22:361-366 (1993). Exemplary inducible promoters include, but are not limited to, that from the ACEI system which responds to copper (Meft, et al., PNAS, 90:4567-4571 (1993)); In2 gene from maize which responds to benzenesulfonamide herbicide safeners (Hershey, et al., Mol. Gen. Genet., 227:229-237 (1991); Gatz, et al., Mol. Gen. Genet., 243:32-38 (1994)); or Tet repressor from Tn10 (Gatz, et al., Mol. Gen. Genet., 227:229-237 (1991)). A particularly preferred inducible promoter is a promoter that responds to an inducing agent to which plants do not normally respond. An exemplary inducible promoter is the inducible promoter from a steroid hormone gene, the transcriptional activity of which is induced by a glucocorticosteroid hormone (Schena, et al., PNAS, 88:0421 (1991)).

B. Constitutive Promoters:

A constitutive promoter is operably linked to a gene for expression in cucumber or the constitutive promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in cucumber.

Many different constitutive promoters can be utilized in the instant invention. Exemplary constitutive promoters include, but are not limited to, the promoters from plant viruses such as the 35S promoter from CaMV (Odell, et al., Nature, 313:810-812 (1985)) and the promoters from such genes as rice actin (McElroy, et al., Plant Cell, 2:163-171 (1990)); ubiquitin (Christensen, et al., Plant Mol. Biol., 12:619-632 (1989); Christensen, et al., Plant Mol. Biol., 18:675-689 (1992)); pEMU (Last, et al., Theor. Appl. Genet., 81:581-588 (1991)); MAS (Velten, et al., EMBO J., 3:2723-2730 (1984)) and maize H3 histone (Lepetit, et al., Mol. Gen. Genet., 231:276-285 (1992); Atanassova, et al., Plant Journal, 2 (3): 291-300 (1992)). The ALS promoter, Xba1/Ncol fragment 5′ to the Brassica napus ALS3 structural gene (or a nucleotide sequence similarity to said Xba1/Ncol fragment), represents a particularly useful constitutive promoter. See PCT Application No. WO 96/30530.

C. Tissue-Specific or Tissue-Preferred Promoters:

A tissue-specific promoter is operably linked to a gene for expression in cucumber. Optionally, the tissue-specific promoter is operably linked to a nucleotide sequence encoding a signal sequence which is operably linked to a gene for expression in cucumber. Plants transformed with a gene of interest operably linked to a tissue-specific promoter produce the protein product of the transgene exclusively, or preferentially, in a specific tissue.

Any tissue-specific or tissue-preferred promoter can be utilized in the instant invention. Exemplary tissue-specific or tissue-preferred promoters include, but are not limited to, a root-preferred promoter, such as that from the phaseolin gene (Murai, et al., Science, 23:476-482 (1983); Sengupta-Gopalan, et al., PNAS, 82:3320-3324 (1985)); a leaf-specific and light-induced promoter, such as that from cab or rubisco (Simpson, et al., EMBO J., 4(11):2723-2729 (1985); Timko, et al., Nature, 318:579-582 (1985)); an anther-specific promoter, such as that from LAT52 (Twell, et al., Mol. Gen. Genet., 217:240-245 (1989)); a pollen-specific promoter, such as that from Zm13 (Guerrero, et al., Mol. Gen. Genet., 244:161-168 (1993)) or a microspore-preferred promoter, such as that from apg (Twell, et al., Sex. Plant Reprod., 6:217-224 (1993)).

Signal Sequences for Targeting Proteins to Subcellular Compartments

Transport of protein produced by transgenes to a subcellular compartment such as the chloroplast, vacuole, peroxisome, glyoxysome, cell wall, or mitochondrion or for secretion into the apoplast, is accomplished by means of operably linking the nucleotide sequence encoding a signal sequence to the 5′ and/or 3′ region of a gene encoding the protein of interest. Targeting sequences at the 5′ and/or 3′ end of the structural gene may determine, during protein synthesis and processing, where the encoded protein is ultimately compartmentalized.

The presence of a signal sequence directs a polypeptide to either an intracellular organelle or subcellular compartment or for secretion to the apoplast. Many signal sequences are known in the art. See, for example Becker, et al., Plant Mol. Biol., 20:49 (1992); Close, P. S., Master's Thesis, Iowa State University (1993); Knox, C., et al., “Structure and Organization of Two Divergent Alpha-Amylase Genes from Barley,” Plant Mol. Biol., 9:3-17 (1987); Lerner, et al., Plant Physiol., 91:124-129 (1989); Fontes, et al., Plant Cell, 3:483-496 (1991); Matsuoka, et al., PNAS, 88:834 (1991); Gould, et al., J. Cell. Biol., 108:1657 (1989); Creissen, et al., Plant J., 2:129 (1991); Kalderon, et al., A short amino acid sequence able to specify nuclear location, Cell, 39:499-509 (1984); Steifel, et al., Expression of a maize cell wall hydroxyproline-rich glycoprotein gene in early leaf and root vascular differentiation, Plant Cell, 2:785-793 (1990).

Foreign Protein Genes and Agronomic Genes

With transgenic plants according to the present invention, a foreign protein can be produced in commercial quantities. Thus, techniques for the selection and propagation of transformed plants, which are well understood in the art, yield a plurality of transgenic plants which are harvested in a conventional manner, and a foreign protein then can be extracted from a tissue of interest or from total biomass. Protein extraction from plant biomass can be accomplished by known methods which are discussed, for example, by Heney and Orr, Anal. Biochem., 114:92-6 (1981).

According to a preferred embodiment, the transgenic plant provided for commercial production of foreign protein is cucumber. In another preferred embodiment, the biomass of interest is seed. For the relatively small number of transgenic plants that show higher levels of expression, a genetic map can be generated, primarily via conventional RFLP, PCR, and SSR analysis, which identifies the approximate chromosomal location of the integrated DNA molecule. For exemplary methodologies in this regard, see Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., 269:284, CRC Press, Boca Raton (1993). Map information concerning chromosomal location is useful for proprietary protection of a subject transgenic plant. If unauthorized propagation is undertaken and crosses made with other germplasm, the map of the integration region can be compared to similar maps for suspect plants, to determine if the latter have a common parentage with the subject plant. Map comparisons would involve hybridizations, RFLP, PCR, SSR, and sequencing, all of which are conventional techniques.

Likewise, by means of the present invention, agronomic genes can be expressed in transformed plants. More particularly, plants can be genetically engineered to express various phenotypes of agronomic interest. Exemplary genes implicated in this regard include, but are not limited to, those categorized below:

A. Genes that Confer Resistance to Pests or Disease and that Encode:

1. Plant disease resistance genes. Plant defenses are often activated by specific interaction between the product of a disease resistance gene (R) in the plant and the product of a corresponding avirulence (Avr) gene in the pathogen. A plant line can be transformed with a cloned resistance gene to engineer plants that are resistant to specific pathogen strains. See, for example, Shoresh, et al., “Characterization of a Mitogen-Activated Protein Kinase Gene from Cucumber Required for Trichoderma-Conferred Plant Resistance,” Plant Physiol., 142(3): 1169-1179 (November 2006) (activation of Trichoderma-induced MAPK (TIPK) gene is necessary for the plant's Trichoderma-conferred defense against bacterial pathogens); Jones, et al., Science, 266:789 (1994) (cloning of the tomato Cf-9 gene for resistance to Cladosporium fulvum); Martin, et al., Science, 262:1432 (1993) (tomato Pto gene for resistance to Pseudomonas syringae pv. tomato encodes a protein kinase); Mindrinos, et al., Cell, 78:1089 (1994) (Arabidopsis RSP2 gene for resistance to Pseudomonas syringae).

2. A Bacillus thuringiensis protein, a derivative thereof or a synthetic polypeptide modeled thereon. See, for example, Geiser, et al., Gene, 48:109 (1986), who disclose the cloning and nucleotide sequence of a Bt δ-endotoxin gene. Moreover, DNA molecules encoding δ-endotoxin genes can be purchased from American Type Culture Collection, Manassas, Va., for example, under ATCC Accession Nos. 40098, 67136, 31995, and 31998.

3. A lectin. See, for example, the disclosure by Van Damme, et al., Plant Mol. Biol., 24:25 (1994), who disclose the nucleotide sequences of several Clivia miniata mannose-binding lectin genes; and Atsushi, et al., “Possible Involvement of Leaf Gibberellins in the Clock-Controlled Expression of XSP30, a Gene Encoding a Xylem Sap Lectin, in Cucumber Roots,” Plant Physiol., 133(4): 1779-1790 (December 2003).

4. A vitamin-binding protein such as avidin. See PCT Application No. US 93/06487, the contents of which are hereby incorporated by reference. The application teaches the use of avidin and avidin homologues as larvicides against insect pests.

5. An enzyme inhibitor, for example, a protease or proteinase inhibitor or an amylase inhibitor. See, for example, Abe, et al., J. Biol. Chem., 262:16793 (1987) (nucleotide sequence of rice cysteine proteinase inhibitor); Huub, et al., Plant Mol. Biol., 21:985 (1993) (nucleotide sequence of cDNA encoding tobacco proteinase inhibitor I); Sumitani, et al., Biosci. Biotech. Biochem., 57:1243 (1993) (nucleotide sequence of Streptomyces nitrosporeus α-amylase inhibitor).

6. An insect-specific hormone or pheromone, such as an ecdysteroid and juvenile hormone, a variant thereof, a mimetic based thereon, or an antagonist or agonist thereof. See, for example, the disclosure by Hammock, et al., Nature, 344:458 (1990), of baculovirus expression of cloned juvenile hormone esterase, an inactivator of juvenile hormone.

7. An insect-specific peptide or neuropeptide which, upon expression, disrupts the physiology of the affected pest. For example, see the disclosures of Regan, J. Biol. Chem., 269:9 (1994) (expression cloning yields DNA coding for insect diuretic hormone receptor); and Pratt, et al., Biochem. Biophys. Res. Comm., 163:1243 (1989) (an allostatin is identified in Diploptera puntata). See also, U.S. Pat. No. 5,266,317 to Tomalski, et al., who disclose genes encoding insect-specific, paralytic neurotoxins.

8. An insect-specific venom produced in nature by a snake, a wasp, etc. For example, see, Pang, et al., Gene, 116:165 (1992), for disclosure of heterologous expression in plants of a gene coding for a scorpion insectotoxic peptide.

9. An enzyme responsible for a hyper-accumulation of a monoterpene, a sesquiterpene, a steroid, hydroxamic acid, a phenylpropanoid derivative, or another non-protein molecule with insecticidal activity.

10. An enzyme involved in the modification, including the post-translational modification, of a biologically active molecule. For example, a glycolytic enzyme, a proteolytic enzyme, a lipolytic enzyme, a nuclease, a cyclase, a transaminase, an esterase, a hydrolase, a phosphatase, a kinase, a phosphorylase, a polymerase, an elastase, a chitinase, and a glucanase, whether natural or synthetic. See PCT Application No. WO 93/02197 in the name of Scott, et al., which discloses the nucleotide sequence of a callase gene. DNA molecules which contain chitinase-encoding sequences can be obtained, for example, from the ATCC under Accession Nos. 39637 and 67152. See also, Kramer, et al., Insect Biochem. Molec. Biol., 23:691 (1993), who teach the nucleotide sequence of a cDNA encoding tobacco hornworm chitinase, and Kawalleck, et al., Plant Mol. Biol., 21:673 (1993), who provide the nucleotide sequence of the parsley ubi4-2 polyubiquitin gene.

11. A molecule that stimulates signal transduction. For example, see the disclosure by Botella, et al., Plant Mol. Biol., 24:757 (1994), of nucleotide sequences for mung bean calmodulin cDNA clones; and Griess, et al., Plant Physiol., 104:1467 (1994), who provide the nucleotide sequence of a maize calmodulin cDNA clone.

12. A hydrophobic moment peptide. See PCT Application No. WO 95/16776 (disclosure of peptide derivatives of tachyplesin which inhibit fungal plant pathogens) and PCT Application No. WO 95/18855 (teaches synthetic antimicrobial peptides that confer disease resistance), the respective contents of which are hereby incorporated by reference.

13. A membrane permease, a channel former, or a channel blocker. For example, see the disclosure of Jaynes, et al., Plant Sci., 89:43 (1993), of heterologous expression of a cecropin-β, lytic peptide analog to render transgenic tobacco plants resistant to Pseudomonas solanacearum.

14. A viral-invasive protein or a complex toxin derived therefrom. For example, the accumulation of viral coat proteins in transformed plant cells imparts resistance to viral infection and/or disease development effected by the virus from which the coat protein gene is derived, as well as by related viruses. See, Beachy, et al., Ann. Rev. Phytopathol., 28:451 (1990). Coat protein-mediated resistance has been conferred upon transformed plants against alfalfa mosaic virus, cucumber mosaic virus, tobacco streak virus, potato virus X, potato virus Y, tobacco etch virus, tobacco rattle virus, and tobacco mosaic virus. Id.

15. An insect-specific antibody or an immunotoxin derived therefrom. Thus, an antibody targeted to a critical metabolic function in the insect gut would inactivate an affected enzyme, killing the insect. See, Taylor, et al., Abstract #497, Seventh Int'l Symposium on Molecular Plant-Microbe Interactions (Edinburgh, Scotland) (1994) (enzymatic inactivation in transgenic tobacco via production of single-chain antibody fragments).

16. A virus-specific antibody. See, for example, Tavladoraki, et al., Nature, 366:469 (1993), who show that transgenic plants expressing recombinant antibody genes are protected from virus attack.

17. A developmental-arrestive protein produced in nature by a pathogen or a parasite. Thus, fungal endo-α-1,4-D-polygalacturonases facilitate fungal colonization and plant nutrient release by solubilizing plant cell wall homo-α-1,4-D-galacturonase. See, Lamb, et al., Bio/technology, 10:1436 (1992). The cloning and characterization of a gene which encodes a bean endopolygalacturonase-inhibiting protein is described by Toubart, et al., Plant 1, 2:367 (1992).

18. A developmental-arrestive protein produced in nature by a plant. For example, Logemann, et al., Bio/technology, 10:305 (1992), have shown that transgenic plants expressing the barley ribosome-inactivating gene have an increased resistance to fungal disease.

B. Genes that Confer Resistance to an Herbicide:

1. An herbicide that inhibits the growing point or meristem, such as an imidazolinone or a sulfonylurea. Exemplary genes in this category code for mutant ALS and AHAS enzyme as described, for example, by Lee, et al., EMBO J., 7:1241 (1988); and Miki, et al., Theor. Appl. Genet., 80:449 (1990), respectively.

2. Glyphosate (resistance conferred by mutant 5-enolpyruvlshikimate-3-phosphate synthase (EPSPS) and aroA genes, respectively) and other phosphono compounds, such as glufosinate (phosphinothricin acetyl transferase (PAT) and Streptomyces hygroscopicus phosphinothricin-acetyl transferase PAT bar genes), and pyridinoxy or phenoxy proprionic acids and cyclohexones (ACCase inhibitor-encoding genes). See, for example, U.S. Pat. No. 4,940,835 to Shah, et al., which discloses the nucleotide sequence of a form of EPSPS which can confer glyphosate resistance. A DNA molecule encoding a mutant aroA gene can be obtained under ATCC Accession No. 39256, and the nucleotide sequence of the mutant gene is disclosed in U.S. Pat. No. 4,769,061 to Comai. See also Umaballava-Mobapathie in Transgenic Research., 8: 1, 33-44 (1999) that discloses Lactuca sativa resistant to glufosinate. European Patent Application No. 0 333 033 to Kumada, et al., and U.S. Pat. No. 4,975,374 to Goodman, et al., disclose nucleotide sequences of glutamine synthetase genes which confer resistance to herbicides, such as L-phosphinothricin. The nucleotide sequence of a phosphinothricin-acetyl-transferase gene is provided in European Patent Application No. 0 242 246 to Leemans, et al., DeGreef, et al., Bio/technology, 7:61 (1989), describe the production of transgenic plants that express chimeric bar genes coding for phosphinothricin acetyl transferase activity. Exemplary of genes conferring resistance to phenoxy proprionic acids and cyclohexones, such as sethoxydim and haloxyfop are the Acc1-S1, Acc1-S2, and Acc1-S3 genes described by Marshall, et al., Theor. Appl. Genet., 83:435 (1992).

3. An herbicide that inhibits photosynthesis, such as a triazine (psbA and gs+ genes) and a benzonitrile (nitrilase gene). Przibilla, et al., Plant Cell, 3:169 (1991), describe the transformation of Chlamydomonas with plasmids encoding mutant psbA genes. Nucleotide sequences for nitrilase genes are disclosed in U.S. Pat. No. 4,810,648 to Stalker, and DNA molecules containing these genes are available under ATCC Accession Nos. 53435, 67441, and 67442. Cloning and expression of DNA coding for a glutathione S-transferase is described by Hayes, et al., Biochem. J., 285:173 (1992).

4. Acetohydroxy acid synthase, which has been found to make plants that express this enzyme resistant to multiple types of herbicides, has been introduced into a variety of plants. See, Hattori, et al., Mol. Gen. Genet., 246:419 (1995). Other genes that confer tolerance to herbicides include a gene encoding a chimeric protein of rat cytochrome P4507A1 and yeast NADPH-cytochrome P450 oxidoreductase (Shiota, et al., Plant Physiol., 106:17 (1994)), genes for glutathione reductase and superoxide dismutase (Aono, et al., Plant Cell Physiol., 36:1687 (1995)), and genes for various phosphotransferases (Datta, et al., Plant Mol. Biol., 20:619 (1992)).

5. Protoporphyrinogen oxidase (protox) is necessary for the production of chlorophyll, which is necessary for all plant survival. The protox enzyme serves as the target for a variety of herbicidal compounds. These herbicides also inhibit growth of all the different species of plants present, causing their total destruction. The development of plants containing altered protox activity which are resistant to these herbicides are described in U.S. Pat. Nos. 6,288,306, 6,282,837, 5,767,373, and International Publication No. WO 01/12825.

C. Genes that Confer or Contribute to a Value-Added Trait, Such as:

1. Increased iron content of the cucumber, for example, by transforming a plant with a soybean ferritin gene as described in Goto, et al., Acta Horticulturae, 521, 101-109 (2000).

2. Increased sweetness of the cucumber by transferring a gene coding for monellin that elicits a flavor 100,000 times sweeter than sugar on a molar basis. See, Penarrubia, et al., Bio/technology, 10: 561-564 (1992). Specific regulatory elements involved in Glc repression also have been identified in the promotors of the cucumber malate synthase. See, Sarah, et al., (1996). “Distinct cis-acting elements direct the germination and sugar responses of the cucumber malate synthase gene.” Mol. Gen. Genet., 250: 153-161.

3. Modified fatty acid metabolism, for example, by transforming a plant with an antisense gene of stearyl-ACP desaturase to increase stearic acid content of the plant. See, Knultzon, et al., PNAS, 89:2625 (1992).

4. Modified carbohydrate composition effected, for example, by transforming plants with a gene coding for an enzyme that alters the branching pattern of starch. See, Shiroza, et al., J. Bacteriol., 170:810 (1988) (nucleotide sequence of Streptococcus mutants fructosyltransferase gene); Steinmetz, et al., Mol. Gen. Genet., 20:220 (1985) (nucleotide sequence of Bacillus subtilis levansucrase gene); Pen, et al., Bio/technology, 10:292 (1992) (production of transgenic plants that express Bacillus lichenifonnis α-amylase); Elliot, et al., Plant Mol. Biol., 21:515 (1993) (nucleotide sequences of tomato invertase genes); Søgaard, et al., J. Biol. Chem., 268:22480 (1993) (site-directed mutagenesis of barley α-amylase gene); and Fisher, et al., Plant Physiol., 102:1045 (1993) (maize endosperm starch branching enzyme II).

D. Genes that Control Male-Sterility:

1. Introduction of a deacetylase gene under the control of a tapetum-specific promoter and with the application of the chemical N-Ac-PPT. See International Publication No. WO 01/29237.

2. Introduction of various stamen-specific promoters. See international publications WO 92/13956 and WO 92/13957.

3. Introduction of the barnase and the barstar genes. See Paul, et al., Plant Mol. Biol., 19:611-622, 1992).

E. Genes that Create a Site for Site Specific DNA Integration:

This includes the introduction of FRT sites that may be used in the FLP/FRT system and/or Lox sites that may be used in the Cre/Loxp system. For example, see Lyznik, et al., Site-Specific Recombination for Genetic Engineering in Plants, Plant Cell Rep., (2003) 21:925-932 and WO 99/25821, which are hereby incorporated by reference. Other systems that may be used include the Gin recombinase of phage Mu (Maeser, et al., (1991); Vicki Chandler, The Maize Handbook, Ch. 118, Springer-Verlag (1994)), the Pin recombinase of E. coli (Enomoto, et al., (1983)), and the R/RS system of the pSR1 plasmid (Araki, et al., (1992)).

F. Genes that Affect Abiotic Stress Resistance:

Genes that affect abiotic stress resistance (including, but not limited to, flowering, pod and seed development, enhancement of nitrogen utilization efficiency, altered nitrogen responsiveness, drought resistance or tolerance, cold resistance or tolerance, and salt resistance or tolerance) and increased yield under stress. For example, see, WO 00/73475, where water use efficiency is altered through alteration of malate; U.S. Pat. Nos. 5,892,009; 5,965,705; 5,929,305; 5,891,859; 6,417,428; 6,664,446; 6,706,866; 6,717,034; 6,801,104; International Publication Nos. WO 2000/060089; WO 2001/026459; WO 2001/035725; WO 2001/034726; WO 2001/035727; WO 2001/036444; WO 2001/036597; WO 2001/036598; WO 2002/015675; WO 2002/017430; WO 2002/077185; WO 2002/079403; WO 2003/013227; WO 2003/013228; WO 2003/014327; WO 2004/031349; WO 2004/076638; WO 98/09521; and WO 99/38977 describing genes, including CBF genes and transcription factors effective in mitigating the negative effects of freezing, high salinity, and drought on plants, as well as conferring other positive effects on plant phenotype; U.S. Publication No. 2004/0148654 and International Publication No. WO 01/36596 where abscisic acid is altered in plants resulting in improved plant phenotype such as increased yield and/or increased tolerance to abiotic stress; International Publication Nos. WO 2000/006341; WO 04/090143; U.S. Application No. 10/817,483 and U.S. Pat. No. 6,992,237, where cytokinin expression is modified resulting in plants with increased stress tolerance, such as drought tolerance, and/or increased yield. Also see International Publication Nos. WO 02/02776; WO 2003/052063; JP2002281975; U.S. Pat. No. 6,084,153; International Publication No. WO 01/64898; U.S. Pat. Nos. 6,177,275 and 6,107,547 (enhancement of nitrogen utilization and altered nitrogen responsiveness). For ethylene alteration, see, U.S. Publication Nos. 2004/0128719; 2003/0166197; and International Publication No. WO 2000/32761. For plant transcription factors or transcriptional regulators of abiotic stress, see, e.g., U.S. Publication Nos. 2004/0098764 or 2004/0078852.

Other genes and transcription factors that affect plant growth and agronomic traits such as yield, flowering, plant growth and/or plant structure, can be introduced or introgressed into plants. See, e.g., International Publication Nos. WO 97/49811 (LHY); WO 98/56918 (ESD4); WO 97/10339; U.S. Pat. No. 6,573,430 (TFL); U.S. Pat. No. 6,713,663 (FT); International Publication Nos. WO 96/14414 (CON); WO 96/38560; WO 01/21822 (VRN1); WO 00/44918 (VRN2); WO 99/49064 (GI); WO 00/46358 (FRI); WO 97/29123; U.S. Pat. Nos. 6,794,560, 6,307,126 (GAI); and International Publication Nos. WO 99/09174 (D8 and Rht), WO 2004/076638, and WO 2004/031349 (transcription factors).

Methods for Cucumber Transformation

Numerous methods for plant transformation have been developed, including biological and physical, plant transformation protocols. See, for example, Miki, et al., “Procedures for Introducing Foreign DNA into Plants” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 67-88 (1993). In addition, expression vectors and in vitro culture methods for plant cell or tissue transformation and regeneration of plants are available. See, for example, Gruber, et al., “Vectors for Plant Transformation” in Methods in Plant Molecular Biology and Biotechnology, Glick and Thompson Eds., CRC Press, Inc., Boca Raton, pp. 89-119 (1993).

A. Agrobacterium-Mediated Transformation:

One method for introducing an expression vector into plants is based on the natural transformation system of Agrobacterium. See, for example, Horsch, et al., Science, 227:1229 (1985); Curtis, et al., Journal of Experimental Botany, 45: 279, 1441-1449 (1994); Torres, et al., Plant cell Tissue and Organic Culture, 34: 3, 279-285 (1993); Dinant, et al., Molecular Breeding, 3: 1, 75-86 (1997). A. tumefaciens and A. rhizogenes are plant pathogenic soil bacteria which genetically transform plant cells. The Ti and Ri plasmids of A. tumefaciens and A. rhizogenes, respectively, carry genes responsible for genetic transformation of the plant. See, for example, Kado, C. I., Crit. Rev. Plant Sci., 10:1 (1991). Descriptions of Agrobacterium vector systems and methods for Agrobacterium-mediated gene transfer are provided by Gruber, et al., supra, Miki, et al., supra, and Moloney, et al., Plant Cell Rep., 8:238 (1989). See also, U.S. Pat. No. 5,591,616 issued Jan. 7, 1997.

B. Direct Gene Transfer:

Several methods of plant transformation, collectively referred to as direct gene transfer, have been developed as an alternative to Agrobacterium-mediated transformation. A generally applicable method of plant transformation is microprojectile-mediated transformation wherein DNA is carried on the surface of microprojectiles measuring 1 μm to 4 μm. The expression vector is introduced into plant tissues with a biolistic device that accelerates the microprojectiles to speeds of 300 m/s to 600 m/s, which is sufficient to penetrate plant cell walls and membranes. Russell, D. R., et al., Pl. Cell. Rep., 12(3, January), 165-169 (1993); Aragao, F. J. L., et al., Plant Mol. Biol., 20(2, October), 357-359 (1992); Aragao, F. J. L., et al., Pl. Cell. Rep., 12(9, July), 483-490 (1993); Aragao, Theor. Appl. Genet., 93: 142-150 (1996); Kim, J., Minamikawa, T., Plant Science, 117: 131-138 (1996); Sanford, et al., Part. Sci. Technol., 5:27 (1987); Sanford, J. C., Trends Biotech., 6:299 (1988); Klein, et al., Bio/technology, 6:559-563 (1988); Sanford, J. C., Physiol. Plant, 7:206 (1990); Klein, et al., Bio/technology, 10:268 (1992).

Another method for physical delivery of DNA to plants is sonication of target cells. Zhang, et al., Bio/technology, 9:996 (1991). Alternatively, liposome and spheroplast fusion have been used to introduce expression vectors into plants. Deshayes, et al., EMBO J., 4:2731 (1985); Christou, et al., PNAS, 84:3962 (1987). Direct uptake of DNA into protoplasts using CaCl₂ precipitation, polyvinyl alcohol, or poly-L-ornithine has also been reported. Hain, et al., Mol. Gen. Genet., 199:161 (1985); Draper, et al., Plant Cell Physiol., 23:451 (1982). Electroporation of protoplasts and whole cells and tissues have also been described. Saker, M., Kuhne, T., Biologia Plantarum, 40(4): 507-514 (1997/98); Donn, et al., In Abstracts of VIIth International Congress on Plant Cell and Tissue Culture IAPTC, A2-38, p. 53 (1990); D'Halluin, et al., Plant Cell, 4:1495-1505 (1992); Spencer, et al., Plant Mol. Biol., 24:51-61 (1994). See also Chupean, et al., Bio/technology, 7: 5, 503-508 (1989).

Following transformation of cucumber target tissues, expression of the above-described selectable marker genes allows for preferential selection of transformed cells, tissues, and/or plants using regeneration and selection methods now well known in the art.

The foregoing methods for transformation would typically be used for producing a transgenic line. The transgenic line could then be crossed with another (non-transformed or transformed) line in order to produce a new transgenic cucumber line. Alternatively, a genetic trait which has been engineered into a particular cucumber cultivar using the foregoing transformation techniques could be moved into another line using traditional backcrossing techniques that are well known in the plant breeding arts. For example, a backcrossing approach could be used to move an engineered trait from a public, non-elite inbred line into an elite inbred line, or from an inbred line containing a foreign gene in its genome into an inbred line or lines which do not contain that gene. As used herein, “crossing” can refer to a simple X by Y cross, or the process of backcrossing, depending on the context.

C. Genetic Marker Profile Through SSR and First Generation Progeny:

In addition to phenotypic observations, a plant can also be identified by its genotype. The genotype of a plant can be characterized through a genetic marker profile which can identify plants of the same variety, or a related variety, or be used to determine or validate a pedigree. Genetic marker profiles can be obtained by techniques such as Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs), which are also referred to as Microsatellites, and Single Nucleotide Polymorphisms (SNPs). For example, see Cregan et al., “An Integrated Genetic Linkage Map of the Soybean Genome,” Crop Science, 39:1464-1490 (1999), and Berry, et al., “Assessing Probability of Ancestry Using Simple Sequence Repeat Profiles: Applications to Maize Inbred Lines and Soybean Varieties,” Genetics, 165:331-342 (2003), each of which are incorporated by reference herein in their entirety.

Particular markers used for these purposes are not limited to any particular set of markers, but are envisioned to include any type of marker and marker profile which provides a means of distinguishing varieties. One method of comparison is to use only homozygous loci for hybrid cucumber Enki.

Primers and PCR protocols for assaying these and other markers are disclosed in the Soybase (sponsored by the USDA Agricultural Research Service and Iowa State University). In addition to being used for identification of hybrid cucumber Enki, and plant parts and plant cells of variety hybrid cucumber Enki, the genetic profile may be used to identify a cucumber plant produced through the use of hybrid cucumber Enki or to verify a pedigree for progeny plants produced through the use of hybrid cucumber Enki. The genetic marker profile is also useful in breeding and developing backcross conversions.

The present invention comprises a cucumber plant characterized by molecular and physiological data obtained from the representative sample of said variety deposited with the American Type Culture Collection (ATCC). Further provided by the invention is a cucumber plant formed by the combination of the disclosed cucumber plant or plant cell with another cucumber plant or cell and comprising the homozygous alleles of the variety.

Means of performing genetic marker profiles using SSR polymorphisms are well known in the art. SSRs are genetic markers based on polymorphisms in repeated nucleotide sequences, such as microsatellites. A marker system based on SSRs can be highly informative in linkage analysis relative to other marker systems in that multiple alleles may be present. See, for example, Gong, L., et al., “Microsatellites for the genus Cucurbita and an SSR-based genetic linkage map of Cucurbita pepo L.,” Theor. Appl. Genet., 117(1): 37-48 (2008 June). Another advantage of this type of marker is that, through use of flanking primers, detection of SSRs can be achieved, for example, by the polymerase chain reaction (PCR), thereby eliminating the need for labor-intensive Southern hybridization. The PCR detection is done by use of two oligonucleotide primers flanking the polymorphic segment of repetitive DNA. Repeated cycles of heat denaturation of the DNA followed by annealing of the primers to their complementary sequences at low temperatures, and extension of the annealed primers with DNA polymerase, comprise the major part of the methodology.

Following amplification, markers can be scored by electrophoresis of the amplification products. Scoring of marker genotype is based on the size of the amplified fragment, which may be measured by the number of base pairs of the fragment. While variation in the primer used or in laboratory procedures can affect the reported fragment size, relative values should remain constant regardless of the specific primer or laboratory used. When comparing varieties, it is preferable if all SSR profiles are performed in the same lab.

A number of promoters have utility for plant gene expression for any gene of interest including, but not limited to, selectable markers, scoreable markers, genes for pest tolerance, disease resistance, nutritional enhancements, and any other gene of agronomic interest. Examples of constitutive promoters useful for cucumber plant gene expression include, but are not limited to, the cauliflower mosaic virus (CaMV) P-35S promoter, which confers constitutive, high-level expression in most plant tissues (see, e.g., Odel, et al., (1985)), including monocots (see, e.g., Dekeyser, et al., (1990); Terada and Shimamoto, (1990)); a tandemly duplicated version of the CaMV 35S promoter, the enhanced 35S promoter (P-e35S) the nopaline synthase promoter (An, et al., (1988)); the octopine synthase promoter (Fromm, et al., (1989)); and the figwort mosaic virus (P-FMV) promoter as described in U.S. Pat. No. 5,378,619 and an enhanced version of the FMV promoter (P-eFMV) where the promoter sequence of P-FMV is duplicated in tandem, the cauliflower mosaic virus 19S promoter, a sugarcane bacilliform virus promoter, a commelina yellow mottle virus promoter, and other plant DNA virus promoters known to express in plant cells.

A variety of plant gene promoters that are regulated in response to environmental, hormonal, chemical, and/or developmental signals can be used for expression of an operably linked gene in plant cells, including promoters regulated by: (1) heat (Callis, et al., (1988)), (2) light (e.g., pea rbcS-3A promoter, Kuhlemeier, et al., (1989); maize rbcS promoter, Schaffner and Sheen, (1991); or chlorophyll a/b-binding protein promoter, Simpson, et al., (1985)), (3) hormones, such as abscisic acid (Marcotte, et al., (1989)), (4) wounding (e.g., wunl, Siebertz, et al., (1989)), or (5) chemicals, such as methyl jasmonate, salicylic acid, or Safener. It may also be advantageous to employ organ-specific promoters (e.g., Roshal, et al., (1987); Schernthaner, et al., (1988); Bustos, et al., (1989)).

Exemplary nucleic acids which may be introduced to the cucumber lines of this invention include, for example, DNA sequences or genes from another species, or even genes or sequences which originate with, or are present in, the same species but are incorporated into recipient cells by genetic engineering methods rather than classical reproduction or breeding techniques. However, the term “exogenous” is also intended to refer to genes that are not normally present in the cell being transformed, or perhaps simply not present in the form, structure, etc., as found in the transforming DNA segment or gene, or genes which are normally present and that one desires to express in a manner that differs from the natural expression pattern, e.g., to over-express. Thus, the term “exogenous” gene or DNA is intended to refer to any gene or DNA segment that is introduced into a recipient cell, regardless of whether a similar gene may already be present in such a cell. The type of DNA included in the exogenous DNA can include DNA which is already present in the plant cell, DNA from another plant, DNA from a different organism, or a DNA generated externally, such as a DNA sequence containing an antisense message of a gene, or a DNA sequence encoding a synthetic or modified version of a gene.

Many hundreds if not thousands of different genes are known and could potentially be introduced into a cucumber plant according to the invention. Non-limiting examples of particular genes and corresponding phenotypes one may choose to introduce into a cucumber plant include one or more genes for insect tolerance, such as a Bacillus thuringiensis (B.t.) gene, pest tolerance, such as genes for fungal disease control, herbicide tolerance, such as genes conferring glyphosate tolerance, and genes for quality improvements such as yield, nutritional enhancements, environmental or stress tolerances, or any desirable changes in plant physiology, growth, development, morphology, or plant product(s). For example, structural genes would include any gene that confers insect tolerance including, but not limited to, a Bacillus insect control protein gene as described in WO 99/31248, herein incorporated by reference in its entirety, and U.S. Pat. Nos. 5,500,365, 5,689,052, and 5,880,275, herein incorporated by reference it their entirety. In another embodiment, the structural gene can confer tolerance to the herbicide glyphosate as conferred by genes including, but not limited to, Agrobacterium strain CP4 glyphosate resistant EPSPS gene (aroA:CP4) as described in U.S. Pat. No. 5,633,435, herein incorporated by reference in its entirety, or glyphosate oxidoreductase gene (GOX) as described in U.S. Pat. No. 5,463,175, herein incorporated by reference in its entirety.

Alternatively, the DNA coding sequences can affect these phenotypes by encoding a non-translatable RNA molecule that causes the targeted inhibition of expression of an endogenous gene, for example via antisense- or cosuppression-mediated mechanisms (see, for example, Bird, et al., (1991)). The RNA could also be a catalytic RNA molecule (i.e., a ribozyme) engineered to cleave a desired endogenous mRNA product (see, for example, Gibson and Shillito, (1997)). Thus, any gene which produces a protein or mRNA which expresses a phenotype or morphology change of interest is useful for the practice of the present invention.

Single-Gene Conversions

When the terms cucumber plant, cultivar, hybrid, or cucumber line are used in the context of the present invention, this also includes any single gene conversions of that line. The term “single gene converted plant” as used herein refers to those cucumber plants which are developed by a plant breeding technique, called “backcrossing,” wherein essentially all of the desired morphological and physiological characteristics of a cultivar are recovered in addition to the single gene transferred into the line via the backcrossing technique. Backcrossing methods can be used with the present invention to improve or introduce a characteristic into the line. The term “backcrossing” as used herein refers to the repeated crossing of a hybrid progeny back to one of the parental cucumber plants for that line, backcrossing 1, 2, 3, 4, 5, 6, 7, 8, or more times to the recurrent parent. The parental cucumber plant which contributes the gene for the desired characteristic is termed the nonrecurrent or donor parent. This terminology refers to the fact that the nonrecurrent parent is used one time in the backcross protocol and therefore does not recur. The parental cucumber plant to which the gene or genes from the nonrecurrent parent are transferred is known as the recurrent parent as it is used for several rounds in the backcrossing protocol. Poehlman & Sleper, (1994); Fehr, (1987). In a typical backcross protocol, the original cultivar of interest (recurrent parent) is crossed to a second line (nonrecurrent parent) that carries the single gene of interest to be transferred. The resulting progeny from this cross are then crossed again to the recurrent parent and the process is repeated until a cucumber plant is obtained wherein essentially all of the desired morphological and physiological characteristics of the recurrent parent are recovered in the converted plant, in addition to the single transferred gene from the nonrecurrent parent.

The selection of a suitable recurrent parent is an important step for a successful backcrossing procedure. The goal of a backcross protocol is to alter or substitute a single trait or characteristic in the original line. To accomplish this, a single gene of the recurrent cultivar is modified or substituted with the desired gene from the nonrecurrent parent, while retaining essentially all of the rest of the desired genetic, and therefore the desired physiological and morphological, constitution of the original line. The choice of the particular nonrecurrent parent will depend on the purpose of the backcross. One of the major purposes is to add some commercially desirable, agronomically important trait to the plant. The exact backcrossing protocol will depend on the characteristic or trait being altered to determine an appropriate testing protocol. Although backcrossing methods are simplified when the characteristic being transferred is a dominant allele, a recessive allele may also be transferred. In this instance it may be necessary to introduce a test of the progeny to determine if the desired characteristic has been successfully transferred.

Many single gene traits have been identified that are not regularly selected for in the development of a new line but that can be improved by backcrossing techniques. Single gene traits may or may not be transgenic. Examples of these traits include, but are not limited to, male sterility, modified fatty acid metabolism, modified carbohydrate metabolism, herbicide resistance, resistance for bacterial, fungal, or viral disease, insect resistance, enhanced nutritional quality, industrial usage, yield stability, and yield enhancement. These genes are generally inherited through the nucleus. Several of these single gene traits are described in U.S. Pat. Nos. 5,777,196, 5,948,957, and 5,969,212, the disclosures of which are specifically hereby incorporated by reference.

Tissue Culture

Further reproduction of the variety can occur by tissue culture and regeneration. Tissue culture of various tissues of cucumber and regeneration of plants therefrom is well known and widely published. For example, reference may be had to Teng, et al., HortScience, 27: 9, 1030-1032 (1992); Teng, et al., HortScience; 28: 6, 669-1671 (1993), Zhang, et al., Journal of Genetics and Breeding, 46: 3, 287-290 (1992); Webb, et al., Plant Cell Tissue and Organ Culture, 38: 1, 77-79 (1994); Curtis, et al., Journal of Experimental Botany, 45: 279, 1441-1449 (1994); Nagata, et al., Journal for the American Society for Horticultural Science, 125: 6, 669-672 (2000); and Ibrahim, et al., Plant Cell, Tissue and Organ Culture, 28(2): 139-145 (1992). It is clear from the literature that the state of the art is such that these methods of obtaining plants are routinely used and have a very high rate of success. Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce cucumber plants having the physiological and morphological characteristics of hybrid cucumber Enki.

As used herein, the term “tissue culture” indicates a composition comprising isolated cells of the same or a different type or a collection of such cells organized into parts of a plant. Exemplary types of tissue cultures are protoplasts, calli, meristematic cells, and plant cells that can generate tissue culture that are intact in plants or parts of plants, such as leaves, pollen, embryos, roots, root tips, anthers, pistils, flowers, seeds, petioles, and the like. Means for preparing and maintaining plant tissue culture are well known in the art. By way of example, a tissue culture comprising organs has been used to produce regenerated plants. U.S. Pat. Nos. 5,959,185, 5,973,234, and 5,977,445 describe certain techniques, the disclosures of which are incorporated herein by reference.

Tissue culture of cucumber can be used for the in vitro regeneration of cucumber plants. Tissues cultures of various tissues of cucumber and regeneration of plants therefrom are well-known and published. By way of example, tissue cultures, some comprising organs to be used to produce regenerated plants, have been described in Burza, et al., Plant Breeding, 114: 4, 341-345 (1995); Cui Hongwen, et al., Cucurbit Genetics Cooperative Report, 22, 5-7 (1999); Pellinen, Angewandte Botanik, 71: 3/4, 116-118 (1997); Kuijpers, et al., Plant Cell Tissue and Organ Culture, 46: 1, 81-83 (1996); Colijn-Hooymans, et al., Plant Cell Tissue and Organ Culture, 39: 3, 211-217 (1994); Lou, et al., HortScience, 29: 8, 906-909 (1994); Tabei, et al., Breeding Science, 44: 1, 47-51 (1994); Sarmanto, et al., Plant Cell Tissue and Organ Culture, 31:3 185-193 (1992); Raharjo, et al., Cucurbit Genetics Cooperative Report, 15, 35-39 (1992); Garcia-Sobo, et al., Cucurbit Genetics Cooperative Report, 15, 40-44 (1992); Cade, et al., Journal of the American Society for Horticultural Science, 115:4 691-696 (1990); Chee, et al., HortScience, 25:7, 792-793 (1990); Kim, et al., HortScience, 24:4 702 (1989); Punja, et al., Plant Cell Rep., 9:2 61-64 (1990). It should also be mentioned that the regeneration of the cucumber after induction of adventitious shoot buds on calli derived from cotyledons, has been described in Msikita, et al., Cucurbit Genetics Cooperative Report, 11: 5-7 (1988), Kim, et al., Plant Cell Tissue Organ Culture, 12: 67-74 (1988); Wehner, et al., HortScience, 16: 759-760 (1981) had previously described the induction of buds on cotyledons. Cucumber plants could be regenerated by somatic embryogenesis. These somatic embryos developed either in cell suspensions derived from calli developed from leaf explants (Chee, et al., Plant Cell Report, 7: 274-277 (1988)) or hypocotyls (Rajasekaran, et al., Annals of Botany, 52: p. 417-420 (1983)), or directly on cotyledonous (Cade, et al., Cucurbit Genetics Cooperative Report, 11:3-4 (1988)) or leaf calli (Malepszy, et al., Pfanzenphysiologie, 111: 273-276 (1983)). It is clear from the literature that the state of the art is such that these methods of obtaining plants are “conventional” in the sense that they are routinely used and have a very high rate of success. Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce cucumber plants having the physiological and morphological characteristics of hybrid cucumber Enki.

Additional Breeding Methods

This invention also is directed to methods for producing a cucumber plant by crossing a first parent cucumber plant with a second parent cucumber plant wherein the first or second parent cucumber plant is a cucumber plant of Enki. Further, both first and second parent cucumber plants can come from hybrid cucumber Enki. Thus, any such methods using hybrid cucumber Enki are part of this invention: selfing, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using hybrid cucumber Enki as at least one parent are within the scope of this invention, including those developed from cultivars derived from hybrid cucumber Enki. Advantageously, this cucumber plant could be used in crosses with other, different, cucumber plants to produce the first generation (F₁) cucumber hybrid seeds and plants with superior characteristics. The cultivar of the invention can also be used for transformation where exogenous genes are introduced and expressed by the cultivar of the invention. Genetic variants created either through traditional breeding methods using hybrid cucumber Enki or through transformation of hybrid cucumber Enki by any of a number of protocols known to those of skill in the art are intended to be within the scope of this invention.

The following describes breeding methods that may be used with hybrid cucumber Enki in the development of further cucumber plants. One such embodiment is a method for developing hybrid cucumber Enki progeny cucumber plants in a cucumber plant breeding program comprising: obtaining the cucumber plant, or a part thereof, of hybrid cucumber Enki, utilizing said plant or plant part as a source of breeding material, and selecting a cucumber Enki progeny plant with molecular markers in common with hybrid cucumber Enki and/or with morphological and/or physiological characteristics selected from the characteristics listed in Table 1. Breeding steps that may be used in the cucumber plant breeding program include pedigree breeding, backcrossing, mutation breeding, and recurrent selection. In conjunction with these steps, techniques such as RFLP-enhanced selection, genetic marker enhanced selection (for example, SSR markers) and the making of double haploids may be utilized.

Another method involves producing a population of hybrid cucumber Enki progeny cucumber plants, comprising crossing hybrid cucumber Enki with another cucumber plant, thereby producing a population of cucumber plants, which, on average, derive 50% of their alleles from hybrid cucumber Enki. A plant of this population may be selected and repeatedly selfed or sibbed with a cucumber plant resulting from these successive filial generations. One embodiment of this invention is the cucumber plant produced by this method and that has obtained at least 50% of its alleles from hybrid cucumber Enki.

One of ordinary skill in the art of plant breeding would know how to evaluate the traits of two plant varieties to determine if there is no significant difference between the two traits expressed by those varieties. For example, see Fehr and Walt, Principles of Cultivar Development, pp. 261-286 (1987). Thus, the invention includes hybrid cucumber Enki progeny cucumber plants comprising a combination of at least two Enki traits selected from the group consisting of those listed in Table 1 or the Enki combination of traits listed in the Summary of the Invention, so that said progeny cucumber plant is not significantly different for said traits than cucumber Enki as determined at the 5% significance level when grown in the same environmental conditions and/or may be characterized by percent similarity or identity to hybrid cucumber Enki as determined by SSR markers. Using techniques described herein, molecular markers may be used to identify said progeny plant as a hybrid cucumber Enki progeny plant. Mean trait values may be used to determine whether trait differences are significant, and preferably the traits are measured on plants grown under the same environmental conditions. Once such a variety is developed its value is substantial since it is important to advance the germplasm base as a whole in order to maintain or improve traits such as yield, disease resistance, pest resistance, and plant performance in extreme environmental conditions.

Progeny of hybrid cucumber Enki may also be characterized through their filial relationship with hybrid cucumber Enki, as, for example, being within a certain number of breeding crosses of hybrid cucumber Enki. A breeding cross is a cross made to introduce new genetics into the progeny, and is distinguished from a cross, such as a self or a sib cross, made to select among existing genetic alleles. The lower the number of breeding crosses in the pedigree, the closer the relationship between hybrid cucumber Enki and its progeny. For example, progeny produced by the methods described herein may be within 1, 2, 3, 4, or 5 breeding crosses of hybrid cucumber Enki.

As used herein, the term “plant” includes plant cells, plant protoplasts, plant cell tissue cultures from which cucumber plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as leaves, pollen, embryos, cotyledons, hypocotyl, roots, root tips, anthers, pistils, flowers, seeds, stems, and the like.

Table 2 compares characteristics for Enki with Incas.

TABLE 2 Characteristic ENKI INCAS Earliness Faster Slower Fruit length Shorter fruit Longer fruit Cladosporium cucumerinum Susceptible Resistant

Deposit Information

A deposit of the hybrid cucumber of this invention is maintained by Enza Zaden USA, Inc., having an address at 7 Harris Place, Salinas, Calif. 93901. Access to this deposit will be available during the pendency of this application to persons determined by the Commissioner of Patent and Trademarks to be entitled thereto under 37 C.F.R. §1.14 and 35 U.S.C. §122. Upon allowance of any claims in this application, all restrictions on the availability to the public of the variety will be irrevocably removed by affording access to a deposit of at least 2,500 seeds of the same variety with the American Type Culture Collection (ATCC), 10801 University Boulevard, Manassas, Va. 20110 or National Collections of Industrial, Food and Marine Bacteria (NCIMB), 23 St. Machar Drive, Aberdeen, Scotland, AB24 3RY, United Kingdom.

While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions, and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, and sub-combinations as are within their true spirit and scope. 

What is claimed is:
 1. A hybrid cucumber seed designated Enki wherein a representative sample of seed has been deposited under ATCC Accession No. ______.
 2. A cucumber plant, or a part thereof, produced by growing the seed of claim
 1. 3. Pollen of the plant of claim
 2. 4. An ovule of the plant of claim
 2. 5. A protoplast produced from the plant of claim
 2. 6. A tissue culture produced from protoplasts or cells from the plant of claim 2, wherein said cells or protoplasts are produced from a plant part selected from the group consisting of leaf, anther, pistil, stem, petiole, root, root tip, fruit, seed, flower, cotyledon, hypocotyl, embryo, and meristematic cell.
 7. A cucumber plant regenerated from the tissue culture of claim
 6. 8. A protoplast produced from the tissue culture of claim
 6. 9. A method for producing a hybrid cucumber seed comprising crossing the cucumber plant of claim 2 with a different cucumber plant and harvesting the resultant hybrid cucumber seed.
 10. A hybrid cucumber seed produced by the method of claim
 9. 11. A hybrid cucumber plant, or a part thereof, produced by growing said hybrid cucumber seed of claim
 10. 12. The method of claim 9, wherein at least one of said cucumber plants is transgenic.
 13. A method of producing an herbicide resistant cucumber plant, wherein said method comprised introducing a gene conferring herbicide resistance into the plant of claim
 2. 14. An herbicide resistant cucumber plant produced by the method of claim 13, wherein the gene confers resistance to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, dicamba, phenoxy proprionic acid, glufosinate, L-phosphinothricin, triazine, and benzonitrile.
 15. A method of producing a pest or insect resistant cucumber plant, wherein said method comprises introducing a gene conferring pest or insect resistance into the cucumber plant of claim
 2. 16. A pest or insect resistant plant produced by the method of claim
 15. 17. The cucumber plant of claim 16, wherein the transgene encodes a Bacillus thuringiensis (Bt) endotoxin.
 18. A method of producing a cucumber plant wherein the method comprises introducing the cucumber plant of claim 2 with a transgene.
 19. A cucumber plant produced by the method of claim
 18. 20. A method of producing a cucumber plant with modified fatty acid metabolism or modified carbohydrate metabolism wherein the method comprises transforming the cucumber plant of claim 2 with a transgene encoding a protein selected from the group consisting of fructosyltransferase, levansucrase, alpha-amylase, invertase, and starch branching enzyme or encoding an antisense of stearyl-ACP desaturase.
 21. A cucumber plant having modified fatty acid metabolism or modified carbohydrate metabolism produced by the method of claim
 20. 